Cursed

Refer to the following video for the solution to the demolition problem.

Exit Theatre Mode

In short, locate the bomb in the right tunnel, then proceed to place the explosives on the glowing holographic spots in the left tunnel and the support at the top of the stairs.

The Heavy Metal achievement (neutralize fifteen enemies with an emplaced weapon) can be done easily here. Simply take control of the machinegun where Khan and the other soldiers are and let the mutants spawn (leave both spots open, or your allies will kill all the mutants and leave you with no valid targets).

The emplaced gun has limited ammunition (about 100 to 200 rounds) so you should only tap-tap the trigger when you have a clear shot with a mutant. With four very tough NPCs tracking and firing on enemies, you should be relatively safe and covered while you rack up your fifteen kills.

When you're done closing the spawn points, locate Khan at the exit (sometimes the A.I. will wander around near the soldiers by the station barricade); only with Khan can you banish the shadows blocking the exit to the next level. Drop through the hole Khan reveals and move to the next map.